The US government’s proposed guidelines for self-driving cars unveiled on Tuesday will ask Google, Tesla and Uber—not to mention the rest of the world’s auto makers—to do something they are not likely to be thrilled about: share data.

Competitors locked in a cut-throat race to bring fully self-driving cars to American roads are being asked to share experiences with “edge cases”, rare scenarios that pose the most vexing safety challenges.

Regulators want them to make vehicle performance assessments public so that all of the companies can learn from the data and enhance safety. “Highly automated vehicles have great potential to use data sharing to enhance and extend safety benefits,” reads page 18 of the transportation department’s document. “Thus, each entity should develop a plan for sharing its event reconstruction and other relevant data with other entities.”

That represents a significant shift for auto makers and tech companies, who fiercely protect their data and aren’t known for collaboration. While there are commercial business practices and consumer privacy issues to be mindful of, there’s no reason companies shouldn’t share information about dangerous incidents, a senior transportation department official told reporters Tuesday.

“People don’t have to make the mistakes their neighbour made,” the official said. “There’s group learning.”

An estimated 35,200 people were killed in US traffic accidents last year, and self-driving cars are seen as a leap forward that will not only save lives but improve mobility for the elderly and disabled. In drafting the guidelines, regulators have looked to the Federal Aviation Administration (FAA) as a model. Airline data is shared with a third-party repository system.

But technology companies will probably bristle at having to share data after an accident involving a self-driving car, said Katie Thomson, former senior counsel at the transportation department and FAA and now a partner at the law firm Morrison & Foerster. “It’s a significant data set,” Thomson said in a phone interview. “That’s where technology companies get territorial.”

The guidelines are voluntary: Regulators are asking, not compelling, companies to share.

“This field is extremely competitive, and data has huge, huge value,” said Jonathan Handel, an attorney with TroyGould who has written about self-driving cars. “Cooperation with the government is not a core value in Silicon Valley. It’s a libertarian environment. This document says ‘we really want you to share your data,’ but they can’t force them to. I don’t think Silicon Valley is going to turn over the keys to the kingdom.” Bloomberg